check O2 sensor, after my cat was gutted i got the same code, when i switched the O2 to an obd-1 i was rich. after putting the cheap universal O2 in the code went away. you may not need a new one but check it out, if you have a spare or a buddy with one hook it up and check it out. mine has always been trouble on bank 1 but in the past i would get an O2 code randomly because something did not read right in the ecu.

btw i am running a jdm b16a with CTR cams and more air flow too with a obd2-b Si ecu.